Light-emitting device and manufacturing method thereof

ABSTRACT

A manufacturing method of a light-emitting device is disclosed. The method includes: providing a semiconductor wafer, including a substrate having a first surface and a second surface opposite to the first surface; and a semiconductor stack on the first surface; removing a portion of the semiconductor stack to form an exposed region; forming a first reflective structure on the exposed region; and providing a radiation on the second surface corresponding to a position of the first reflective structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of TaiwanApplication Number 105100979 filed on Jan. 13, 2016, which isincorporated by reference in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to a light-emitting device and amanufacturing method thereof, more particularly, to a light-emittingdevice having high brightness.

Description of the Related Art

Light-emitting diode (LED) is an optoelectronic device composed ofp-type semiconductor and n-type semiconductor. LEDs emit light bycombination of the carriers at p-n junction and can be widely applied inoptical display devices, traffic signals, data storage devices,communication devices, lighting devices and medical instruments.Conventional processes of manufacturing LEDs include forming asemiconductor stack on a substrate by epitaxy process so as to form awafer. After the epitaxy process, a dicing process is performed todivide the wafer into a plurality of light-emitting diode chips.

Conventional wafer dicing methods include forming two groups of scribinglines which are perpendicular to each other on the surface of the LEDwafer, and then performing cleaving process by sawing the LED waferalong the two groups of the scribing lines and splitting the wafer intoa plurality of LED chips along the scribing lines. Another wafer dicingmethod includes irradiating laser beam on the surface of the LED wafer.Modification regions are formed on interior of the substrate due to theirradiation of the laser beam and then the LED wafer is separated into aplurality of LED chips along the modification regions by force. However,being limited to the conventional dicing method, the yield of dicing maybe degraded when the dicing streets of the LED wafer are narrow orduring the process of splitting the LED wafer. Besides, if the power ofthe laser is not controlled under an optimized condition whileperforming wafer dicing, in addition to the degraded yield, the laserbeam may damage the semiconductor stack of the wafer.

SUMMARY OF THE DISCLOSURE

A method of manufacturing a light-emitting device is disclosed. Themethod includes: providing a semiconductor wafer, including a substratehaving a first surface and a second surface opposite to the firstsurface; and a semiconductor stack on the first surface; removing aportion of the semiconductor stack to form an exposed region; forming afirst reflective structure on the exposed region; and providing aradiation on the second surface corresponding to a position of the firstreflective structure.

A light-emitting device is disclosed. The light-emitting deviceincludes: a substrate; a semiconductor stack formed on the substrate,comprising a first semiconductor layer, a second semiconductor layer andan active layer between the first and the second semiconductor layers; aperipheral region surrounding the active layer and the secondsemiconductor layer; and a first reflective structure formed on theperipheral region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1I show a manufacturing method of a light-emitting device inaccordance with one embodiment of present application.

FIG. 2 shows a diagram demonstrating the reflectivity vs. wavelength ofthe light-emitting device.

FIGS. 3A and 3B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with another embodiment ofpresent application.

FIGS. 4A and 4B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with another embodiment ofpresent application.

FIGS. 5A and 5B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with another embodiment ofpresent application.

FIGS. 6A and 6B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with another embodiment ofpresent application.

FIGS. 7A-7F show a manufacturing method of a light-emitting device inaccordance with another embodiment of present application.

FIGS. 8A and 8B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with another embodiment ofpresent application.

FIGS. 9A and 9B respectively show a top view and a cross-sectional viewof a light-emitting device in accordance with a further embodiment ofpresent application.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference is made in detail to the preferred embodiments of the presentapplication, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

FIGS. 1A to 1I show a manufacturing method for light-emitting device inaccordance with one embodiment of the present application. As shown inFIG. 1A, a substrate 10 comprising a first surface 101 and a secondsurface 102 is provided. A semiconductor stack 20 is formed on the firstsurface 101 by epitaxy process so as to form a wafer 1. The substrate 10can be sapphire, silicon, SiC, GaN or GaAs. The semiconductor stack 20comprises a first semiconductor layer 22 and a second semiconductorlayer 26 sequentially formed on the first surface 101 and an activelayer 24 interposed between the first semiconductor layer 22 and thesecond semiconductor layer 26. The substrate 10 can be a patternedsubstrate; i.e. the first surface 101 of the substrate 10 can bepatterned. Lights emitted from the active layer 24 can be refracted bythe patterned structure of the substrate 10 so that the brightness ofthe light-emitting device is improved. Furthermore, the patternedstructure retards or restrains the dislocation due to lattice mismatchbetween the substrate 10 and the semiconductor stack 20 so that theepitaxy quality of the semiconductor stack 20 is improved. Besides, abuffer layer (not shown) is formed on the first surface 101 of thesubstrate 10 before forming the semiconductor stack 20. The buffer layercan also reduce the lattice mismatch described above and restrain thedislocation so as to improve the epitaxy quality. The firstsemiconductor layer 22 and the second semiconductor layer 26 havedifferent polarities by doping n-type dopant or p-type dopant. Forexample, the first semiconductor layer 22 is an n-type semiconductor andthe second semiconductor layer 26 is a p-type semiconductor. Thematerial of the semiconductor stack 20 comprises III-V compoundsemiconductor comprising one element selected from the groups composedof Al, Ga, In, N, P, As and Si, such as a compound semiconductor likeAlGaInP, AlN, GaN, AlGaN, InGaN or AlInGaN. The structure of the activelayer 24 can be single heterostructure (SH), double heterostructure(DH), double-side heterostructure (DDH) or multi-quantum well (MQW)structure.

Next, as shown in FIG. 1B and FIG. 1C, a part of the secondsemiconductor layer 26 and the active layer 24 are removed to expose thefirst semiconductor layer 22 by etching process. An exposed region 201is formed accordingly. FIG. 1B is a cross-sectional view along line A-A′of an enlarged region W in FIG. 1C. The exposed region 201 comprises aplurality of first exposed regions 201 a perpendicular with each otherand a plurality of second exposed regions 201 b. In the followingprocess, the second exposed regions 201 b are used to form electrodesthereon. The first exposed regions 201 a function as the dicing streetsin wafer dicing process. The wafer 1 is diced along the dicing streetsformed by the first exposed regions 201 a. Then, as shown in FIG. 1D, afirst reflective structure 12 a is formed on a surface of the firstexposed region 201 a and a second reflective structure 12 b is formed onthe second semiconductor layer 26. The first reflective structure 12 aand the second reflective structure 12 b are formed in the same processand have the same material. The region R is an enlarged view of thefirst reflective structure 12 a and the second reflective structure 12 bin FIG. 1D. As shown in FIG. 1D, the first reflective structure 12 a andthe second reflective structure 12 b have stacks of dielectric material.The stack of dielectric material comprises a plurality of pairs ofdielectric layer 121 and 122 with different refractive indexesalternately laminated. The dielectric material comprises SiOx, Si₃N₄,Al₂O₃, Ti_(X)O_(Y), Ta₂O₅, Nb₂O₅, ZrO₂ or a combination thereof.

Then, referring to FIG. 1E, a transparent conductive layer 16 is formedon the second semiconductor layer 26 and the second reflective structure12 b. The transparent conductive layer 16 can covers entirely the secondreflective structure 12 b. Next, a first electrode 30 a is formed on asurface of the first semiconductor layer 22 in the second exposed region201 b, and a second electrode 30 b is formed on the transparentconductive layer 16. The second electrode 30 b is formed on a positioncorresponding to the second reflective structure 12 b. An area of thesecond electrode 30 b is equal to or smaller than that of the secondreflective structure 12 b. The first electrode 30 a and the secondelectrode 30 c are disposed oppositely on the semiconductor stack 20 andrespectively near the shorter edges of the semiconductor stack 20. FIG.1F shows a cross-sectional view along a direction perpendicular to theline A-A′ in FIG. 1C which passes the second electrode 30 b. In anotherembodiment as shown in FIG. 1G, the structure is similar with that inFIG. 1E. The difference between the structures in FIG. 1E and FIG. 1G isthat the transparent conductive layer 16 has an opening 28 at a positioncorresponding to the second reflective structure 12 b so that parts ofthe top surface of the second reflective structure 12 b are exposed. Ina cross-sectional view, a width of the opening 28 is smaller than awidth of the second reflective electrode 12 b and/or the maximum widthof the second electrode 30 b. The second electrode 30 b is formed on thetransparent conductive layer 16 and the second reflective structure 12 band fills in the opening 28 to contact the second reflective structure12 b. In another embodiment of the present application, both the secondreflective structure 12 b and the transparent conductive layer 16 haveopenings under the second electrode 30 b. In a cross-sectional view, awidth of the opening is slightly smaller than the maximum width of thesecond electrode 30 b so that the second electrode 30 b passes thesecond reflective structure 12 a and the transparent conductive layer 16via the opening and contacts the second semiconductor layer 26.

Next, as shown in FIG. 1H, providing a radiation, for example, a laser50 on the second surface 102 of the substrate 10 along a pathcorresponding to the dicing streets formed by the first exposed region201 a. The laser 50 can be stealth dicing laser (SD laser). The laserfocuses on the interior of the substrate 10 along the dicing streets andforms modification region 60 in the interior of the substrate 10. Themodification region 60 becomes stealth dicing lines. In one embodiment,the stealth dicing laser can be repeatedly performed and focus on theinterior of the substrate with different depths to form several stealthdicing lines on the same cross section inside the substrate 10. Inanother embodiment, before applying the laser dicing, a reflective layer(e.g. distributed Bragg reflector, DBR) is formed on the second surface102 of the substrate 10 to improve light extraction of thelight-emitting device. While the stealth dicing laser is focused on theinterior of the substrate 10, parts of the laser 50 may pass through thefirst surface 101 of the substrate 10 and scatter into the semiconductorstack 20. As a result, the semiconductor stack 20 is damaged. Byselecting the dielectric material, the thickness and the number of thedielectric layers, the first reflective structure 12 a can reflect andguide the laser 50 which passes through the substrate 10 away from thesemiconductor stack 20. Thus, the laser 50 which scatters into thesemiconductor stack 20 is reflected by the first reflective structure 12a and the damage of the semiconductor stack 20 caused by the laser 50can be prevented and/or reduced. For example, when the wavelength of theapplied stealth dicing laser 50 is about 1064 nm, the first reflectivestructure 12 a can be a stack comprising 12 pairs of SiO₂ layer withthickness of 183 nm and TiO₂ layer with thickness of 112 nm alternatelylaminated. Referring to the simulation result shown in FIG. 2, whenapplying the stealth dicing laser with a wavelength of 1064 nm, thefirst reflective structure 12 a with the stack described above almostreflects the laser at this wavelength entirely. Finally, a force isapplied on the front side or back side of the wafer 1. Thus, the wafer 1is split along the stealth dicing lines inside the substrate 10 and thefirst reflective structure 12 a is also separated accordingly. Then, thewafer 1 is separated into a plurality of light-emitting device 2.

FIG. 3A shows a top view of a light-emitting device 2 according to themanufacturing method described above in the present application. FIG. 3Bis a cross-sectional view along line A-A′ in FIG. 3A. The light-emittingdevice 2 comprises a substrate 10 having a first surface 101, a secondsurface 102, a plurality of side surfaces 103, and a semiconductor stack20 formed on the first surface 101 of the substrate 10. The firstsurface 101 of the substrate 10 may comprise a patterned structure (notshown) which can enhance the brightness and epitaxy quality of thelight-emitting device 2. The semiconductor stack 20 comprises a firstsemiconductor layer 22, a second semiconductor layer 26, and an activelayer 24 between the first semiconductor layer 22 and the secondsemiconductor layer 26. The semiconductor stack 20 comprises a firstexposed region 201 a and a second exposed region 201 b which expose thefirst semiconductor layer 22 by removing a portion of the secondsemiconductor layer 26 and the active layer 24. A first reflectivestructure 12 a is formed on the first exposed region 201 a and a firstelectrode 30 a is formed on the second exposed region 201 b. Asdescribed in the aforementioned manufacturing method of thelight-emitting device, since the first reflective structure 12 a isdisposed on the dicing street formed by the first exposed region 201 abefore dicing the wafer, when viewing from a top, the first reflectivestructure 12 a surrounds the active layer 24 and the secondsemiconductor layer 26. There is no first reflective structure 12 abetween a sidewall of the active layer 24 and adjacent first electrode30 a or between a sidewall of the second semiconductor layer 26 andadjacent first electrode 30 a. A second reflective structure 12 b and atransparent conductive layer 16 covering the second reflective structure12 b and the second semiconductor layer 26 are formed on the secondsemiconductor layer 26. A second electrode 30 b is formed on thetransparent conductive layer 16 at a position corresponding to thesecond reflective structure 12 b. The area of the second reflectivestructure 12 b can be equal to or slightly larger than the area of thesecond electrode 30 b, and the second reflective structure 12 b and thesecond electrode 30 b may have the same or similar shape. In themanufacturing method of the present application, since the wafer 1 hasmodification regions in the substrate 10 formed by the stealth dicinglaser and the wafer 1 is cleaved into the plurality of light-emittingdevice 2 by an external force along the modification regions, the sidesurfaces 103 of the split substrate 10 have a textured region (notshown) that is substantially parallel to the first surface 101 and/orthe second surface 102; wherein the textured region has stripe pattern.That is, the striped textured regions are the modification regionscaused by the laser beam focusing on the interior of the substrate 10.When the stealth laser dicing is performed repeatedly, a plurality ofstripe textured regions is formed. In addition, the light-emittingdevice 2 may have a reflective layer (not shown) on the second surface102 of the substrate 10 to enhance the light extraction efficiency.

Since the first reflective structure 12 a and the second reflectivestructure 12 b are formed at the same time in the same process, thefirst reflective structure 12 a and the second reflective structure 12 bhave the same material. The first and second reflective structures 12 aand 12 b comprise dielectric stacks composed of a plurality of pairs ofdielectric materials with different refractive indexes alternatelylaminated. The dielectric materials comprise SiOx, Si₃N₄, Al₂O₃,Ti_(X)O_(Y), Ta₂O₅, Nb₂O₅, ZrO₂, or a combination thereof. In oneembodiment, the first reflective structure 12 a and the secondreflective structure 12 b are stacks of SiO₂ layers and TiO₂ layersalternately laminated, and the stack comprises 2 to 12 pairs of SiO₂layer and TiO₂ layer. Since the second reflective structure 12 b isformed between the second semiconductor layer 26 and the transparentconductive layer 16 at a position corresponding to the second electrode30 b and with a shape corresponding to the second electrode 30 b, thesecond reflective structure 12 b made by the dielectric materialprohibits current from directly injecting into the second semiconductorlayer 26 from the second electrode 30 b. Then, electron-holerecombination under the second electrode 30 b is reduced. Therefore, thelight-emitting efficiency of the region other than the second electrode30 b can be improved.

In a light-emitting device 3 in accordance with another embodiment ofthe present application, a patterned first reflective structure can beformed on the first semiconductor layer 22 in the first exposed region201 a around the light-emitting device 3 and/or a patterned secondreflective structure can be formed on the second semiconductor layer 26.FIGS. 4A and 4B show an example of such structure. FIG. 4B is across-sectional view taken along the line A-A′ of FIG. 4A. The secondelectrode 301 includes a bonding portion 301 a and an extending portion301 b extending from the bonding portion 301 a. A plurality of patternedsecond reflective structures 32 are provided on the second semiconductorlayer 26 and under the second electrode 301. The second reflectivestructures 32 a are located under the bonding portion 301 a and theplurality of patterned second reflective structures 32 b is locatedunder the extensions 301 b. The plurality of patterned second reflectivestructures 32 b can be composed of a plurality of discontinuous dots,blocks or line structures. The gap between the plurality of patternedsecond reflective structures 32 b increases as the distance from thebonding portion 301 a increases. That is, as the plurality of patternedsecond reflective structures 32 b is more far away from the bondingportion 301 a, the intervals among the plurality of patterned secondreflective structures 32 b become wider. In a light-emitting device 4 inaccordance with another embodiment of the present application shown inFIG. 5A, a patterned first reflective structure 34 is formed on thefirst exposed region 201 a. FIG. 5B is a cross-sectional view takenalong the line B-B′ in FIG. 5A. The patterned first reflectivestructures 34 formed by dielectric materials scatter light emitted bythe light-emitting device 4 around the light-emitting device 4 therebyenhance light-extraction efficiency of the light-emitting device 4. Thearrangements of the first and the second reflective structures of thelight-emitting device in accordance with the present application are notlimited thereto and may comprise different arrangements depending on thepurpose of current confinement or light-extraction.

FIGS. 6A and 6B are a top view and a cross-sectional view taken alongline B-B′ of a light-emitting device 5 in accordance with anotherembodiment of the present application, respectively. The surface of thefirst semiconductor layer 22 of the first exposed region 201 a aroundthe light-emitting device 5 has a light guide structure 220 and a firstreflective structure 34 formed thereon. The light guide structure 220 iscomposed of a plurality of pillars 220′ with a height between 1 μm and10 μm. The light guide structure 220 is formed by etching the firstsemiconductor layer 22 in the first exposed region 201 a by using thepatterned first reflective structure 34 as a mask after patterning thefirst reflective structure 34. For example, the etching process can bedry etching and the etching depth can be 1 μm to 10 μm. As a result, aportion of the first semiconductor layer 22 not covered by the patternedfirst reflective structure 34 is removed, and the plurality of pillars220′ are formed on the surface of the first semiconductor layer 22. Thelight-emitting efficiency of the light-emitting device 5 is improved bythe patterned first reflective structures 34 and the light guidestructures 220 on the first exposed region 201 a around thelight-emitting device 5.

FIGS. 7A to 7F show a manufacturing method of a light-emitting device inaccordance with another embodiment in the present application. As shownin FIG. 7A, after the semiconductor stack 20 is epitaxially grown on thefirst surface 101 of the substrate 10, the wafer 11 is formed. Parts ofthe second semiconductor layer 26 and the active layer 24 are removed byetching process and the first semiconductor layer 22 is exposed to forma plurality of platforms 203. In another embodiment, the first surface101 of the substrate 10 may have a patterned structure (not shown).Next, a portion of the first semiconductor layer 22 in the platforms 203is further removed by etching to expose the first surface 101 of thesubstrate 10 so that a plurality of trenches 18 is formed. A pluralityof light-emitting cells 70 is separated from each other by trenches 18.Next, as shown in FIG. 7B, the trenches 18 include isolation regions 18′where an insulating layer 14 is on a portion of the trenches 18 and anexposed region 18″ where no insulating layer 14 is provided between twoadjacent light-emitting cells 70. The insulating layer 14 in theisolation region 18′ covers the sidewall of the adjacent light-emittingunits 70, the first semiconductor layer 22, and the second semiconductorlayer 26. In subsequent processes, the exposed regions 18″ are used todefine dicing streets in the wafer dicing process. The wafer 11 is dicedalong the dicing streets. Next, as shown in FIG. 7C, a first reflectivestructure 42 a is formed on the first surface 101 in the exposed region18″, and a second reflective structure 42 b is formed on the secondsemiconductor layer 26 of parts of the light-emitting cells 70. Thefirst and second reflective structures 42 a and 42 b are formedsimultaneously and made by the same material. The first reflectivestructure 42 a and the second reflective structure 42 b are dielectricstacks composed of a plurality of pairs of dielectric layers withdifferent refractive indexes alternately laminated. The dielectricmaterials comprise SiOx, Si₃N₄, Al₂O₃, Ti_(X)O_(Y), Ta₂O₅, Nb₂O₅, ZrO₂,or a combination thereof.

Then, as shown in FIG. 7D, a transparent conductive layer 16 is formedon the surface of the second semiconductor layer 26 and the secondreflective structure 42 b of each light-emitting cell 70. Thetransparent conductive layer 16 can cover the second reflectivestructure 42 b entirely. Next, an electrical connection 36 is formed onthe insulating layer 14, a first electrode 30 a is formed on the firstsemiconductor layer of the light-emitting cell 70 c, and secondelectrode 30 b is formed on the transparent conductive layer 16 at aposition corresponding to the second reflective structure 42 b of thelight-emitting cell 70 a. The electrical connection 36 covers theinsulating layer 14 and extends onto the first semiconductor layer 22and the transparent conductive layer 16 of the adjacent light-emittingcells so that the light-emitting cells 70 a to 70 c are electricallyconnected in series. The first electrode 30 a and the second electrode30 b can be connected to an external power supply or an electroniccomponent by wiring or bonding. As a result, the light-emitting cells 70a-70 c are defined as a light-emitting array. The second electrode 30 bis formed on a corresponding position of the second reflective structure42 b, and the area of the second electrode 30 b can be equal to orslightly smaller than that of the second reflective structure 42 b. Inanother embodiment of the present application, the transparentconductive layer 16 and the second reflective structure 42 b haveopenings (not shown) at the position corresponding to the secondelectrode 30 b so as to expose a portion of the upper surface of thesecond semiconductor layer 26. The second electrode 30 b is formed onthe transparent conductive layer 16 and the second reflective structure42 b, and fills in the opening to contact the second semiconductor layer26.

Next, as shown in FIG. 7E, the second surface 102 of the substrate 10 isirradiated by a radiation, for example, the laser 50 on a positioncorresponding to the dicing streets formed by the exposed region 18″.The laser 50 can be a stealth dicing laser. The laser 50 focuses on theinterior of the substrate 10 along the dicing streets and then themodification regions 60 (i.e. stealth dicing lines) are formed. Inanother embodiment, a reflective layer (not shown) can be formed on thesecond surface of the substrate 10 prior to performing stealth dicinglaser to improve light-extraction efficiency of the light-emittingdevice. When the stealth dicing laser focusing on the interior of thesubstrate 10, a portion of the laser 50 may scatter into thesemiconductor stack through the first surface 101 of the substrate 10thereby damage the semiconductor stack 20. By selecting suitabledielectric material, the thickness and the number of the dielectriclayers of the first reflective structure 42 a, the first reflectivestructure 42 a is able to reflect and guide the laser 50 which passesthrough the substrate 10 away from the semiconductor stack 20. Thus, thelaser 50 which scatters into the semiconductor stack 20 is reflected bythe first reflective structure 42 a, and the damage in the semiconductorstack 20 caused by the power of the laser 50 can be prevented andreduced. Finally, as shown in FIG. 7F, force is applied to the wafer 11to split the wafer 11 along the stealth dicing lines inside thesubstrate 10, and the first reflective structure 42 a is also split. Thewafer 11 is separated into a plurality of light-emitting device 7. Eachlight-emitting device 7 includes a light-emitting array havinglight-emitting cells 70 a to 70 c connected in series.

FIG. 8A is a top view of the light-emitting device 7 in accordance withthe manufacturing method of the present application, and FIG. 8B is across-sectional view taken along the line A-A′ in FIG. 8A. Thelight-emitting device 7 comprises a substrate 10 having a first surface101, a second surface 102, a plurality of side surfaces 103, andlight-emitting cells 70 a-70 c disposed on the first surface 101 of thesubstrate 10. Each light-emitting cell includes a light-emitting stack20, and the light-emitting cells 70 a-70 c are spatially separated fromeach other by the trenches 18. The bottom of the trench 18 is the firstsurface 101 of the substrate 10. The first surface 101 within the trench18 and the sidewalls of the adjacent light-emitting cells 70 have aninsulating layer 14 disposed thereon to form an isolation region 18′.The electrical connection 36 is on the insulating layer 14. Theelectrical connection 36 covers the insulating layer 14 and contacts thefirst semiconductor layer 22 and the transparent conductive layer 16 ofthe adjacent light-emitting cells to electrically connect thelight-emitting cells 70 a to 70 c in series. The second reflectivestructure 42 b and the transparent conductive layer 16 covering thesecond reflective structure 42 b and the second semiconductor layer 26is formed on the surface of the second semiconductor layer 26 of thelight-emitting cell 70 a. The second electrode 30 b is disposed on thetransparent conductive layer 16 at a position corresponding to thesecond reflective structure 42 b. The first reflecting structure 42 a isprovided on the first surface 101 of the substrate 10 as in theaforementioned manufacturing method of the light-emitting device. Sincethe first reflecting structure 42 a is provided on the dicing streetformed by the exposed region 18″ before dicing the wafer 11, the firstreflective structure 42 a simultaneously surrounds the firstsemiconductor layer 22, the active layer 24, and the secondsemiconductor layer 26 of the light-emitting cells 70 a to 70 b in a topview. Since the first reflective structure 42 a and the secondreflective structure 42 b are formed at the same time, the firstreflective structure 42 a and the second reflective structure 42 b havethe same material and comprise dielectric stacks composed by a pluralityof pairs of dielectric materials having different refractive indexesalternately laminated. In another embodiment, the structure of thelight-emitting device is similar to that of the light-emitting device 7,and the difference is that the insulating layer 14 can be formed in thesame process as the first reflecting structure 42 a and the secondreflecting structure 42 b, and the material of the insulating layer 14can be the same as that of the first reflecting structure 42 a and thesecond reflecting structure 42 b. The insulating layer 14 can be areflective structure with a dielectric stack composed of a plurality ofpairs of dielectric materials having different refractive indexesalternately laminated.

In the light-emitting device 8 in accordance with another embodiment ofthe present application, the patterned first reflective structure 42 a′can be provided between the adjacent light-emitting cells 70 a to 70 c.The structure and material of the patterned first reflective structure42 a′ can be the same as the reflective structure described above orsimilarly modified based on the disclosure. As shown in FIGS. 9A and 9Bwhich is a cross-sectional view taken along the line A-A′ of FIG. 9A,the patterned first reflective structure 42 a′ is provided on the firstsurface 101 in the isolation region 18′. The patterned first reflectivestructure 42 a′ composed of dielectric material has a function of lightguiding. Therefore, the lateral light emitted from the light-emittingcells 70 a to 70 c is prevented from being absorbed by each other due tothe close distance between each light-emitting cell that degrades thelight-emitting efficiency.

It will be apparent to those having ordinary skill in the art thatvarious modifications and variations can be made to the devices inaccordance with the present disclosure without departing from the scopeor spirit of the disclosure. In view of the foregoing, it is intendedthat the present disclosure covers modifications and variations of thisdisclosure provided they fall within the scope of the following claimsand their equivalents.

What is claimed is:
 1. A method of manufacturing a light-emittingdevice, comprising: providing a semiconductor wafer, comprising: asubstrate having a first surface and a second surface opposite to thefirst surface; and a semiconductor stack on the first surface of thesubstrate; removing a portion of the semiconductor stack to form anexposed region; forming a first reflective structure on the exposedregion; and providing a radiation on the second surface of the substratecorresponding to a position of the first reflective structure.
 2. Themethod of claim 1, wherein the semiconductor stack is a light-emittingstack, comprising a first semiconductor layer, an active layer and asecond semiconductor layer formed on the first surface.
 3. The method ofclaim 1, wherein the exposed region comprises one or a plurality ofdicing streets.
 4. The method of claim 1, further comprising focusingthe radiation on an interior of the substrate to form a plurality ofdicing lines in the substrate; and splitting the semiconductor waferinto a plurality of light-emitting devices along the plurality of dicinglines.
 5. The method of claim 2, further comprising forming a secondreflective structure on the second semiconductor layer; wherein thefirst and the second reflective structures have the same material. 6.The method of claim 1, wherein the first reflective structure is capableof reflecting the radiation.
 7. The method of claim 2, wherein removingthe portion of the semiconductor stack to expose the first semiconductorlayer to form the exposed region; wherein the exposed region comprisesone or more dicing streets and forming the first reflective structure onthe first semiconductor layer in the dicing streets.
 8. The method ofclaim 2, wherein removing the portion of the semiconductor stack toexpose the first surface of the substrate to form the exposed region;wherein the exposed region comprises one or more dicing streets andforming the first reflective structure on the first surface in thedicing streets.
 9. The method of claim 5, wherein the first and thesecond reflective structures comprise dielectric stacks, and thedielectric stack is formed by a plurality of dielectric layers withdifferent refractive indexes alternately laminated.
 10. Thelight-emitting diode device of claim 5, further comprising: forming atransparent conductive layer on the second reflective structure and thesecond semiconductor layer; and forming a second electrode on thetransparent conductive layer at a position corresponding to the secondreflective structure.
 11. A light-emitting device, comprising: asubstrate; a light-emitting stack on the substrate, comprising: a firstsemiconductor layer; a second semiconductor layer; and an active layerformed between the first semiconductor layer and the secondsemiconductor layer; a peripheral region surrounding the active layerand the second semiconductor layer; and a first reflective structureformed on the peripheral region.
 12. The light-emitting device of claim11, further comprising: a second electrode on the second semiconductorlayer; and a second reflective structure disposed between the secondelectrode and the second semiconductor layer; wherein the firstreflective structure and the second reflective structure have the samedielectric stacks, and the dielectric stacks are formed by a pluralityof pairs of dielectric layers having different refractive indexesalternately laminated.
 13. The light-emitting device of claim 11,wherein the first reflective structure comprises a dielectric stack, andthe dielectric stack is formed by a plurality of dielectric layers withdifferent refractive indexes alternately laminated.
 14. Thelight-emitting device of claim 11, wherein the first reflectivestructure is capable of reflecting the radiation.
 15. The light-emittingdevice of claim 11, wherein the peripheral region comprises an exposedsurface of the first semiconductor layer, and the first reflectivestructure is formed on the exposed surface of the first semiconductorlayer.
 16. The light-emitting device of claim 11, wherein: one or morelight-emitting stacks on the substrate to form a plurality of thelight-emitting stacks; the peripheral region comprises an exposedsurface on a peripheral of the substrate where the light-emitting stackis not provided thereon, and the peripheral region surrounds the firstsemiconductor layers, the active layers, and the second semiconductorlayers of the plurality of the light-emitting stacks; and the firstreflective structure is formed on the exposed surface of the substrate.17. The light-emitting device of claim 16, wherein the first reflectivestructure has a patterned structure and/or the first reflectivestructure is formed between any two light-emitting stacks of theplurality of light-emitting stacks.
 18. The light-emitting device ofclaim 15, wherein the first reflective structure comprises a patternedstructure.
 19. The light-emitting device of claim 18, wherein thesurface of the first semiconductor layer in the peripheral regioncomprises light guiding structures.
 20. The light-emitting device ofclaim 12, wherein the second reflective structure comprises a patternedstructure.